Device for adjusting a rotor blade of a wind energy turbine

ABSTRACT

The device for adjusting a rotor blade of a wind energy turbine is provided with a driving device ( 12 ) for driving an adjusting e ement ( 24 ) for selectably rotating the rotor blade ( 26 ) in both directions about its longitudinal axis ( 28 ), an energy storage unit ( 30 ) and a free-running means ( 32 ) adapted to be selectively activated, said free-running means ( 32 ), in its activated state, allowing rotation of the rotor blade ( 26 ) by means of energy stored in the energy storage unit ( 30 ) only in one of the two directions up to a desired rotational position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for adjusting a rotor blade of a wind energy turbine. In particular, the invention relates to a device for adjusting (rotating) a rotor blade of a wind energy turbine into a desired rotational position (rotor blade location) without the rotor blade being capable of rotating back in particular, the rotor blade can be locked in the end position or any other rotor position).

2. Description of Related Art

For safety reasons, wind energy turbines require the rotor blades to be capable of being adjusted into a desired (parking) position and locked in said position when a disturbance occurs. For this purpose, systems exist in which the rotor blades are adjusted via their electrical drives, which in cases of emergencies are operated via accummulators or similar electrical energy storages, into the parking position. Those systems are described in DE-A-197 20 025, DE-A-196 44 705, and DE-A-42 21 783. Further, systems are known in which the energy for adjusting the rotor blades into the parking position is provided by mechanical energy storages, such as spring-type storages.

From WO-A-99/23384 and U.S. Pat. No. 6,428,274 a device for adjusting a rotor blade is known in which a locking element directly acts on the driving shaft of a motor for driving the rotor blade.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a device for adjusting a rotor blade of a wind energy turbine, by means of which device, in case of an emergency, the rotor blade can be reliably adjusted into a desired position and locked in said position, if necessary.

According to the invention, this object is achieved with a device for adjusting a rotor blade of a wind energy turbine, the device being provided with:

-   -   a driving device for driving a pitiching element for selectably         rotating the rotor blade in both directions about its         longitudinal axis,     -   an energy storage unit, and     -   a free-running means adapted to be selectively activated, said         free-running means allowing, in its activated state, rotation of         the rotor blade by means of energy stored in the energy storage         unit only in one of the two directions of rotation up to a         desired rotational position.

According to the invention, the device comprises a free-running means adapted to be selectively activated which, e.g. in case of an emergency, is actively or passively connected (in the latter case as a fail-safe system) such that the rotor blade is rotatable by means of the energy from an energy storage only in one direction of rotation into the desired (parking) position. In each rotating position backward rotation of the rotor blade is inhibited since the free-running means produces a direction-selective non-positive connection between the rotor blade or an element directly or indirectly connected with the rotor blade, and the locking element. The free-running element is e.g. configured as a ratchet comprising a toothed element the toothing of which meshes with a locking pawl or a similar locking element. The toothed element may in particular be a brake disk of a locking brake of the rotor blade adjusting mechanism.

The free-running means prevents the rotor blade, once it has assumed the (parking) position or any other position, from being rotated backwards. Thus adjusting moments applied on the rotor blade by the wind or mass forces do not lead to backward rotation of the rotor blade.

In the invention a mechanical energy storage, e.g. a spring-type storage and in particular a coil spring-type storage, can advantageously be used, said storage being driven by a driving unit. The free-running means appropriately engages the more rapidly rotating (drive or driven) shaft of a gear which is normally provided in rotor blade adjusting systems. The gear can be configured e.g. as a toothed gear and/or a belt drive.

Generally, the free-running means comprises a first element adapted to be movable in two opposite directions, in particular directions of rotation, and a second element adapted to be placed in and out of engagement with the first element, wherein the second element, when in engagement with the first element, allows the first element to be moved only in one of its two directions. For reasons of safety it is preferred that the second element is biased into the position, in which it is in engagement with the first element, by means of a biasing element and is adapted to be moved into the out-of-engagement position against the biasing force by means of an actuator. Thus, in case of energy failure, activating the free-running means does not require any electrical energy since the automatic deactivation of the actuator alone, which occurs in the case of energy failure, activates the free-running means.

The advantages of the device according to the invention can be summarized as follows:

-   -   the rotor blade can be fixed within the overall adjusting range         (applies unrestrictedly to the brake, but only restrictedly to         the free-running means since the free-running means still allows         rotational movement in one direction),     -   movement of the rotor blade in the (undesired) direction         opposite to the direction of rotation is inhibited during         rotation of the rotor blade into the desired position,     -   due to a high gear ratio a low retaining force of the         free-running means is necessary on the rapidly rotating shaft,         which requires a lower constructional expenditure and a less         stable and thus more inexpensive structure than in the case of         locking the rotor blade directly on the blade bearing,     -   the rotor blade is always “retained” in a comparatively low-load         parking position (in which the rotor blade assumes a feathered         position), whereby the overall wind energy turbine and in         particular the tower and the rotor blades are relieved,     -   fail-safe activation is possible.

BRIEF DESCRIPTION OF THE DRAWING

A preferred embodiment of the invention is schematically shown in the drawing.

Hereunder the invention is described in detail with reference to the drawing.

DETAILED DESCRIPTION OF THE INVENTION

In the drawing a rotor blade adjusting mechanism 10 is shown which comprises an electrical driving device 12 which rotatingly drives the drive shaft 14 of a gear 16. This shaft 14 carries the brake disk 18 of a locking brake device 20 configured as a fail-safe, passive or active brake. The driven shaft 22 of the gear 16 drives a gearwheel 24 which meshes with an internal ring gear 25 of a rotor blade 26 which is rotatable about its longitudinal axis 28. Via the gear 16 a mechanical (spring-type) energy storage 30 is supplied. The rotor blade adjusting mechanism 10 is further provided with an end position damper and stop, which is not absolutely necessary for the invention and is thus not shown in the drawing for the sake of clarity of the invention.

The brake disk 18 forms part of a switchable free-running means 32 comprising a locking element 34 which is movable between a locking position and a release position. In its locking position the locking element 34 is in engagement with the brake disk 18 to prevent the latter from rotating in one of the two directions of rotation. In this embodiment the brake disk 18 is therefore provided with a toothing 36 with which meshes a meshing end 38 of the locking element 34 (which is e.g. supported such that it is pivotable about an axis 39) in the locking position. The locking element 34 is biased into the locking position by means of a biasing spring 40 and can be moved out of said locking position and into the release position and maintained in this position with the aid of an actuator 42.

Normally, the locking brake 20 is released, and by driving the drive device 12 the rotor blade 26 can be adjusted into a position suitable for operation of the wind energy turbine. Mechanical energy, which is not supplied to the system, is stored in the energy storage 30, and the free-running means 32 is deactivated, i.e. the locking element 34 is out of engagement with the brake disk 18. In case of emergency, the driving device 12 is switched off so that the rotor blade 26 is rotated into the desired parking position (e.g. the feathered or 90° pitch or negatively feathered pitch) by the energy from the energy storage 30. The free-running means 32 is activated by switching off the actuator 42 so that the locking element 34 automatically meshes with the toothing 36 of the brake disk 18. Due to the sawtooth structure of the brake disk 18 the latter can now rotate only in one direction of rotation, while it is prevented from rotating in the opposite direction of rotation by the locking element 34. Thus the rotor blade 26, too, is rotatable only in one of its two directions of rotation. As soon as the rotor blade 26 has reached its parking position, which is detectable e.g. by sensors and in particular limit switches (not shown), the locking brake 20 is activated and fixes the rotor blade 26 via the brake disk 18. Due to use of the spring-type storage, end position stops which are elastic or damped in any other way should be used in the end positions.

Although the invention has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope of the invention as defined by the claims that follow. It is therefore intended to include within the invention all such variations and modifications as fall within the scope of the appended claims and equivalents thereof. 

1. Device for adjusting a rotor blade of a wind enegy turbine, comprising a driving device (12) for driving an adjusting element (24) for selectably rotating the rotor blade (26) in both directions about its longitudinal axis (28), an energy storage unit (30), and a free-running means (32) adapted to be selectively activated, said free-running means (32) allowing, in its activated state, rotation of the rotor blade (26) by means of energy stored in the energy storage unit (30) only in one of the two directions of rotation up to a desired rotational position.
 2. Device according to claim 1, wherein the driving device (12) comprises a gear (16) having a drive shaft (14) and a driven shaft (22) connected with the adjusting element (24), and that the free-running means (32) is arranged at the more rapidly rotatable shaft (14,22) of the gear (16).
 3. Device according to claim 1 or 2, further comprising a locking brake (20) which locks the rotor blade (26) when the predetermined rotational position of the rotor blade has been reached.
 4. Device according to claim 3, wherein the locking brake (20) comprises a brake disk (18), and that the free-running means (32) engages the brake disk (18).
 5. Device according to one of claims 1 to 4, wherein the energy storage unit (30) is configured as a spring-type storage adapted to be operated by the driving device (12).
 6. Device according to one of claims 1 to 5, wherein the gear (16) is a toothed gear or a belt drive.
 7. Device according to one of claims 1 to 6, wherein the free-running means (32) comprises a first element (18) adapted to be freely movable in two opposite directions and a second element (34) adapted to be placed in and out of engagement with the first element (18), wherein the second element (34), when in engagement with the first element (18), allows the first element (18) to be moved only in one of its two directions.
 8. Device according to claim 7, wherein the first element (18) of the free-running means (32) is configured as a brake disk of a locking brake (20) for locking the rotor blade (26).
 9. Device according to claim 8, wherein the second element (34) is biased into the position, in which it is in engagement with the first element (18), by means of a biasing element (40) and is adapted to be moved into the out-of-engagement position against the biasing force by means of an actuator (42). 